Hi There.

I hope somebody can help me with this question.  I am a writer doing some write-ups on bitcoin as a whole for my employer.
I found that "solving a block" generates 25 BTC (currently).
Aside from the monetary gain, are there any other reasons why a block should be 'solved'?  I just had this theory that since it is a decentralize system, there must be more to 'solving a block' and why people were given a reward when they solved one...
I hope somebody can help.
Thanks in advance!